Just after 8:50 a.m. BST (3:50 a.m. ET) both major benchmarks are trading at a substantial loss, and have fallen to near one-month lows. Brent crude, the European benchmark is at $38.25 per barrel, down 1.09% on the day, while American WTI crude has slipped 1.36% to $36.29. That extends Brent's losses since March 30th to nearly 7%, and WTI's losses beyond 8% in less than a week's trading.

Since then, prices have recovered somewhat, and just before 10:30 a.m. BST (5:30 a.m ET) brent has returned to gains, up around 0.1%, while WTI is now down just 0.3%.

Here's how that looks:

Investing.com Along with the Iranian supply increase, the price of oil was also driven lower by worries that a freeze in production — which was agreed in late February— isn't actually going to happen.